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BIO 140 Human Biology I - Questions and Solutions

Layers of the Skin - Solutions

Review Questions

1. The papillary layer of the dermis is most closely associated with which layer of the epidermis?

  1. stratum spinosum
  2. stratum corneum
  3. stratum granulosum
  4. stratum basale

2. Langerhans cells are commonly found in the ________.

  1. stratum spinosum
  2. stratum corneum
  3. stratum granulosum
  4. stratum basale

3. The papillary and reticular layers of the dermis are composed mainly of ________.

  1. melanocytes
  2. keratinocytes
  3. connective tissue
  4. adipose tissue

4. Collagen lends ________ to the skin.

  1. elasticity
  2. structure
  3. color
  4. UV protection

5. Which of the following is not a function of the hypodermis?

  1. protects underlying organs
  2. helps maintain body temperature
  3. source of blood vessels in the epidermis
  4. a site to long-term energy storage

 

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Critical Thinking Questions

1. What determines the color of skin, and what is the process that darkens skin when it is exposed to UV light?

Solution: The pigment melanin, produced by melanocytes, is primarily responsible for skin color. Melanin comes in different shades of brown and black. Individuals with darker skin have darker, more abundant melanin, whereas fair-skinned individuals have a lighter shade of skin and less melanin. Exposure to UV irradiation stimulates the melanocytes to produce and secrete more melanin.

2. Cells of the epidermis derive from stem cells of the stratum basale. Describe how the cells change as they become integrated into the different layers of the epidermis.

Solution: As the cells move into the stratum spinosum, they begin the synthesis of keratin and extend cell processes, desmosomes, which link the cells. As the stratum basale continues to produce new cells, the keratinocytes of the stratum spinosum are pushed into the stratum granulosum. The cells become flatter, their cell membranes thicken, and they generate large amounts of the proteins keratin and keratohyalin. The nuclei and other cell organelles disintegrate as the cells die, leaving behind the keratin, keratohyalin, and cell membranes that form the stratum lucidum and the stratum corneum. The keratinocytes in these layers are mostly dead and flattened. Cells in the stratum corneum are periodically shed.

 

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OpenStax, Layers of the Skin. OpenStax CNX. Jul 3, 2013 http://cnx.org/contents/471cb008-6900-476c-8a65-539fdc592b75@5. © Jul 3, 2013 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License 3.0 license.